/*
 * Remove Nth Node From End of List
Given a linked list, remove the nth node from the end of list and return its head.

For example,

   Given linked list: 1->2->3->4->5, and n = 2.

   After removing the second node from the end, the linked list becomes 1->2->3->5.
Note:
Given n will always be valid.
Try to do this in one pass.
 */
package com.xinpan.exercise;

public class RemoveNthNodeFromTheEndofList {
    public ListNode removeNthFromEnd(ListNode head, int n) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(head == null)
            return null;
        
        ListNode pre = head;
        ListNode cur = head;
        for(int i = 0; i < n; i++)
            cur = cur.next;
        if(cur == null)
            return head.next;
        
        while(cur.next != null)
        {
            pre = pre.next;
            cur = cur.next;
        }
        pre.next = pre.next.next;
        return head;
    }
}
